1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to a power supply device having an overvoltage cutoff function, an image display device, and a method of cutting off overvoltage, and more particularly, to a power supply device having an overvoltage cutoff function, an image display device, and a method of cutting off overvoltage, that can prevent damage to a power supply device due to an unstable AC input voltage by providing an overvoltage cutoff circuit in the power supply device, and enable a user to recognize the cutoff of the power supply to the power supply device due to the overvoltage by displaying the power supply cutoff state.
2. Description of the Related Art
Referring to FIG. 1, a general power supply device comprises an AC power input unit 110, a rectifying unit 120, a capacitor 130, and a DC-to-DC converter 140.
The AC power input unit 110 receives an AC power from an AC power supply. The rectifying unit 120 rectifies the AC supply voltage input to the AC power input unit 110 and performs smoothing of the rectified voltage to output a DC voltage. The rectifying unit 120 generally comprises bridge diodes.
The DC voltage rectified by the rectifying unit 120 is charged in the capacitor 130, and the DC-to-DC converter 140 changes the voltage from the capacitor 130 to a specified voltage level.
However, in some areas in which AC supply voltages are unstably supplied (e.g., Commonwealth of Independent States (CIS), China, Southeast Asia, Central and South America, and so forth) or in areas in which AC power is supplied using independent electric generators, the conventional power supply devices are frequently damaged due to AC overvoltage, and product liability problems occur in some cases.
In such areas, AC supply voltage of more than 300V, which exceeds the rated voltage, may be supplied, and this may cause the capacitor in the power supply device to be damaged. In this case, the voltage being applied to the capacitor becomes 1.414 times the input voltage. If the voltage being applied to the capacitor exceeds the rated voltage of the capacitor over a specified time period, the capacitor may lose its dielectric strength, and an internal dielectric material may explode with the generation of noise and the occurrence of a fire.